Compounds exhibiting biocidal activity are well known in the art. For example, pyrithione salts, such as zinc pyrithione, are known to provide excellent biocidal activity, including broad spectrum anti-bacterial and anti-fungal activity. There are many uses for these pyrithiones. By way of illustration, U.S. Pat. No. 4,818,436 discloses the use of pyrithiones in metal working fluids, U.S. Pat. No. 4,401,770 discloses urethane shoe inserts having antimicrobial activity; and U.S. Pat. No. 4,935,061 discloses their use in paints.
Despite the excellent biocidal (particularly fungicidal) activity attributable to pyrithlone salts, these compounds do have drawbacks for certain applications, most notably limited solubility in certain organic solvents and aqueous media. Accordingly, new compounds exhibiting excellent biocidal activity, but also exhibiting good solubility in organic solvents would be useful to the biocides manufacturing community.
One compound that exhibits good biocidal efficacy and solubility in shampoo formulations is 1-hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)-2-Pyridone. Unfortunately, this compound is more expensive to manufacture than otherwise might be desired. This compound and related compounds are disclosed in U.S. Pat. No. 3,883,545; their use in combating dandruff is described in U.S. Pat. No. 4,185,106; and their use in an antidandruff shampoo is described in U.S. Pat. No. 4,711,775. U.S. Pat. No. 4,916,228 discloses the preparation of a broad class of 1-hydroxy-2-pyridones by a process comprising reacting a pyrone having a specified structural formula with a hydroxylammonium salt in the presence of at least one alkali metal carbonate and/or hydrogen carbonate.
A technical journal publication entitled "Quantitative Structure-Activity Analysis in a Series of Antimycotically Active N-Hydroxypyridones", Journal of Medicinal Chemistry, 1974, Vol. 17, No. 7, p. 753, describes a variety of 1-hydroxy-substituted-2-pyridones, including those having para-substitutions of --SCH.sub.2 C.sub.6 H.sub.4 Cl (compound 15 in Table II thereof) and --OCH.sub.2 C.sub.6 H.sub.4 Cl (compound 16 in Table II thereof), as having antimycotic activity. However, the method of preparation of these compounds is not described in this technical publication, and it is believed that these compounds were made from 6-chloro-2-pyrone which is not commercially available.
Other new biocides providing desired solubility characteristics, as well as new processes for their preparation, would be highly desired by the biocides manufacturing community.